It is known that production of data-storage optical discs, of the type commercially identified by abbreviations "CD"' or "DVD", involves manufacture by a precise injection-molding step, which disc must be subsequently submitted to several different processing work stations to enable reading and/or providing the disc with appropriate protection for the data contained therein.
As a result, the semi-finished disc obtained from a molding process is loaded onto an assembly provided with different work stations each of which carries out a predetermined operation contemplated in the disc processing cycle. For instance, discs of the type commonly referred to as "CD" are first submitted to a metallizing treatment, i.e. vacuum plating is performed on their surface bearing the recorded data. In a subsequent step, the metallized surface is submitted to a lacquering treatment involving deposition of a protective layer of transparent plastic material thereon. The lacquered disc is then submitted to a lacquer-drying step to be afterwards transferred to an outlet station provided with a collecting magazine or other means adapted to move the finished disc away from the manufacturing assembly.
A control station is often provided upstream of the outlet station which performs a qualitative inspection of the finished discs and an additional selecting station transfers faulty discs, if any, to an auxiliary collection magazine.
Presently, transfer of the individual discs being processed from each work station to a subsequent work station is performed by mechanical handling devices which include a support arm provided which is reciprocally movable about a vertical axis and has a pick-up head at its end. This pick-up head by means of suction-cups or other appropriate means to be actuated pneumatically, picks the disc up from a work station and deposits it in the immediately following work station.
In other prior assemblies manufacturing optical discs, a turntable is also utilized in combination with the above-described handling devices. Such turntables have circumferentially distributed seatings each adapted to engage a respective optical disc in order to submit it, as a result of successive angular rotations imparted to the turntable, to the action of different work stations disposed about the turntable itself.
From the foregoing, it has been found that the use of many mechanical handling devices operating independently of each other to perform transfer of the discs between two specific locations within the assembly complicates the structure as (1) more expensive space is required for housing the handling devices and enabling movement of the same, and (2) a specific drive unit is required for each handling device, the operation of which must occur in synchronism with all of the machine components of the manufacturing assembly. Moreover, in this prior handling devices, each handling device is only utilized for half of its operating cycle, since its return stroke after transfer of the disc is an idle stroke.
On the other hand, while the turntable presents the possibility of interlocking different work stations to a single turntable without requiring the latter to execute idle strokes, such a turntable is extremely bulky, especially if the number of work stations to be associated with the turntable is relatively high. In addition, the internal areas of a turntable are practically unused, therefore leading to costly space requirements with no benefit received.
It has further been found that the overall dimensions and/or the operating requirements of known transferring devices present a hindrance in planning, in connection with the different operating stations.